Look closely at cocktail in the East End (7)

I believe the answer is:

eyeball

I'm a little stuck... Click here to teach me more about this clue!

'look' is the definition.
(I know this)

I can't explain the remainder of the clue.

(Other definitions for eyeball that I've seen before include "One faces one in confrontation" , "Watch" , "Spherical optical organ" , "something in orbit" , "Socket filler" .)

I've seen this clue in The Daily Express.

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